Detection, identification, quantification, and characterization of biomolecules or cells of interest through testing of biological samples is an important aspect in the fields of medical diagnostics and biomedical research. Biological solutions, such as blood, spinal fluid, cell culture and urine, are routinely analyzed for their microscopic particle concentrations.
Existing bacteria cell counting methods include inexpensive but manual cell counting hemacytometer and expensive large instruments such as flow cytometer, plate reader, as well as bacterial colony measurement. The manual cell counting device is extremely tedious and inconsistent and is prone to human errors and cleaning procedures. Flow cytometry requires large quantity of samples, due to the utilization of lasers, is very expensive and requires well-trained professionals to perform the instrument in order to obtain accurate results. Bacteria colony and measurement by optical density has also been used in cell counting, but the preparation is tedious and prone to contamination. In addition, it requires days and even weeks for the bacteria culture to be accurately measurable.
Recently, an automated cell counting instrument has been developed by Nexcelom Bioscience that utilizes a microfluidic counting chamber, which can automatically count cells larger than 2 μm in diameter.
There is, however, a pressing need for efficient and consistent imaging and counting instrument and methods for biological particles with diameters less than 2 μm, such as bacteria or parasites.